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MARSDEN FUND NEWSLETTERNo 27· April 2004
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| Professor David Besson, from the University of Kansas,
and Dr Steve Churchwell in December 2003, carefully trying to locate the top of a RICE detector hole which has been covered with the previous year's snowdrift. |
Although we are completely unaware of it, every second, trillions of tiny particles from space pass through each of us. Known as neutrinos, these particles have zero electric charge and extremely small masses, features which mean that, fortunately for us, they very rarely interact with any matter that they encounter.
This effective invisibility actually means that neutrinos are very important in a number of areas of physics and cosmology. Because they do not interact very often with matter, neutrinos can travel unaltered in straight lines through vast distances across the Universe, and can therefore provide valuable information about other galaxies. Neutrinos may also hold the key to some of the most hotly debated cosmological phenomena and puzzles in particle physics, including speculative theories such as supersymmetry, mysteries such as the nature of Dark Matter, and phenomena such as gamma-ray bursts.
Although it is the fact that neutrinos rarely interact with matter that makes them so useful to study, this feature also means that they can be extremely difficult to detect. Now, a team of scientists from the University of Canterbury is trying to solve this problem, by using neutrino detectors buried in Antarctic ice.
The Radio Ice Cerenkov Experiment (RICE) is a collaborative experiment which aims to detect ultrahigh-energy neutrinos from space through their interactions with the Antarctic ice cap. The University of Canterbury's RICE group, funded by a Marsden grant, is led by DR Jenni Adams and includes experimentalist DR Steve Churchwell, postdoctoral fellow DR Suruj Seunarine, and several postgraduate students. Other participants in the project include physicists at the University of Kansas, the Bartol Research Institute at the University of Delaware, and MIT.
When a neutrino interacts with the ice, it loses all of its energy, which is then converted to a particle which has a significant mass, such as an electron. This electron in turn gives its energy to thousands of other lower energy electrons, positrons, and photons. These particles are still energetic enough to be travelling extremely fast, and as they travel through the ice, they emit electromagnetic waves. This radio emission can then be detected from distances up to about a kilometer away.
The RICE detector has been collecting data for about five years. During the winter, the experiment runs with an automatic triggering system which forces it to save data whenever it detects signals which could be neutrinos. In the summer, RICE project members work in Antarctica itself.
Back at Canterbury University, the RICE group is working on analysing several aspects of the experiment. One area of research involves studying the radio emissions from showers of thousands of particles produced in the atmosphere when high energy cosmic rays interact kilometer above the Earth's surface. The term 'cosmic rays' includes any particles produced by explosions in space, and includes neutrinos, protons, and other charged particles. "The reasons this is interesting, is that it is actually still a mystery as to what the source of the highest energy cosmic rays is", said DR Adams, "and it will also help us to calibrate our detector for detecting neutrinos". To date, the research has revealed that the radio emission exists, and that some will reach the RICE detector. The next stage is to determine how well RICE can measure this particular radio emission.
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| Front Row: Graduate students Philip Wahrlich, Pauline
Harris, and Kahae Han, and visiting researcher DR Derek Boyd (on sabbatical from the University of Maryland, USA). Back Row: DR Suruj Seunarine, group leader DR Jenni Adams, and DR Steve Churchwell. |
PhD student Pauline Harris is also looking at the RICE dataset, to see if there is any unusual activity around the times of recorded gamma ray bursts. Gamma ray bursts are short-lived bursts of gamma ray photons that are detected approximately once per day from random directions in the sky. They are believed to have come from the explosive death of massive stars in distant galaxies. Various models of gamma ray bursts are predicted to produce ultrahigh-energy neutrinos, which, if they exist, may be traced using the RICE detector. "So far", said DR Adams, "we have not seen any neutrinos, which means if any are given out, it is a smaller number than some of the models predict".
Although the Marsden grant is finished, the RICE detector continues to gather data. Those neutrinos that end up within the few cubic kilometres of Antarctic ice cap surveyed by RICE may well help resolve some of the long-standing mysteries of the Universe. DR Adams, her collaborators, and her students wait patiently.
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For more information, contact
DR Jenni Adams or DR Suruj Seunarine Department of Physics and Astronomy University of Canterbury Private Bag 4800, Christchurch Tel: (03) 364 2581 Email: jenni.adams@canterbury.ac.nz or surujhdeo.seunarine@canterbury.ac.nz |
The flora of Antarctica has always fascinated scientists. Botanist Joseph Hooker, who accompanied James Clark Ross's 1839-43 expedition to Antarctica, published a six-volume work Flora Antarctica. The rocks which Captain Robert Scott's team in 1912 carried on their unsuccessful pull from the South Pole to the safety of Ross Island contained the fossilised remains of a deciduous conifer, Glossopteris.
Now a Marsden-funded group lead by palynologist DR Ian Raine from the Institute of Geological and Nuclear Sciences is undertaking a three-year project aimed at giving more insight into Antarctic flora.
"What we want to do is get a fuller picture of the Antarctic flora", says DR Raine. The project also aims to understand better the link between Antarctica's ancient flora and plants now growing on New Zealand's sub-Antarctic islands and in the alpine areas of New Zealand and other southern lands.
Evidence from fossil pollen and spores, and other plant fossils, has already begun to sketch out the story of Antarctica's flora: when Antarctica cooled 35 million years ago, its diverse rainforest was lost. About 24 million years ago, the landscape of Antarctica changed from one covered with woodlands to one of tundra. The tundra too was overwhelmed by the continent's ice sometime between 15 and 3 million years ago.
Based on results of earlier work on material from the Ross Sea region, DR Raine's group suggests that Antarctica may have been a conduit for plants to travel from South America to Australia and New Zealand. And, some of the Antarctic plant groups may have migrated northwards to New Zealand, Australia and the sub-Antarctic Islands.
To try and find more about the sub-Antarctic strand of the story, DR Raine and his colleagues from Victoria University, botanist Professor Philip Garnock-Jones and postdoctoral fellow DR Vanessa Thorn, are studying Auckland and Campbell Islands. In March they made a two-week journey to the islands, to collect samples of Pliocene and Miocene strata. "At the moment all we know is the last 15,000 years", says DR Raine.
The group also plans to carry out detailed further investigation of Antarctic fossil material found in the Ross Sea region, comparing that with pollen and spores of modern plants. And to find out if there is a connection from the ancient flora of Antarctica to modern-day New Zealand (Antarctica may have had an 'alpine' vegetation at the same time as the mountains of New Zealand were beginning to grow) the group will be studying the molecular genetics of modern plants, hunting for the 'ghosts' of the Antarctic flora in New Zealand alpine plants. "The aim is to link the modern DNA evidence about plant relationships with the geological history of their fossil relatives, to trace the migrations and evolution of such plants as buttercups, chickweeds, and New Zealand flax", says DR Raine.
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Pictured is the grave of M. Duris, a member of the French expedition that visited Campbell Island in 1874 to observe the Transit of Venus. Duris, a technician in the scientific party, died from typhoid fever and is buried on the point opposite Venus Cove where the French team built an observation platform. Left to right: Ian Raine, Vanessa Thorn, Phil Garnock-Jones. According to Ian Kerr's book Campbell Island: A History the sub-Antarctic island has other reminders of the French presence: Garden Cove is the site of a garden planted by an advance party a year before the Transit. (The vegetables did not survive 'ruine de nos espérances culinaires' was the lament of the French); the island is also dotted with the names of the scientific committee that planned France's observation of the Transit. Sadly, after years of preparation, December 9, 1874 was cloudy. Kerr writes: "at the moment of contact the cloud came over again. Some minutes later they glimpsed for 20 seconds Venus half on to the sun's disc, but that was all." |
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For more information, contact
DR Ian Raine Institute of Geological and Nuclear Sciences PO Box 30-368, Lower Hutt Tel: (04) 570 4844 Email: i.raine@gns.cri.nz |
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Marsden Fund preliminary proposals, 2004
February, March and April have been busy months with the receipt of the preliminary proposals and the preparation for the assessment meetings which took place at the end of March and the beginning of April. The Marsden Fund Council met on 17 April to make the final decisions on which preliminary proposals for 2004 will be invited to submit full proposals. The invitations have now been sent to the successful applicants.
This year, there were 972 preliminary proposals - 744 standard proposals and 228 Fast-Start proposals. This is a considerable increase in numbers compared to last year when 741 Preliminary proposals - 612 standard and 129 Fast-Start proposals were received.
Feedback
All applicants to this year's round have been advised whether or not they are invited to submit a full proposal. The question of feedback for unsuccessful applicants is often raised. Unfortunately, given the large number of applications, it is unrealistic to offer individual, written feedback; instead this year (as last year) unsuccessful applicants whose proposals that are rated in the top third are advised of this. The Marsden Fund, however, does offer advice to applicants in the lead up to the closing date for preliminary applications and is happy to provide speakers for seminars. And institutions themselves are increasingly providing feedback on proposals, prior to submission.
Panels
53 panellists (plus the 8 panel convenors) were involved this year in making
recommendations to the Marsden Fund Council. The Council and the Royal Society
are very appreciative of the commitment of the panellists, who each read anywhere
from 60 to 120 applications. Panellists need to be active researchers with the
ability to assess proposals outside of their own field. They are appointed by
the Royal Society, after discussion with panel convenors, primarily for their
specialist expertise.
However, attention is also paid to ensuring that the panels are as representative
as possible of the research community. There is no official procedure for nominations.
However, institutions or individual who wish to make informal nominations may
do so. These will be brought to the attention of panel convenors when vacancies
arise.
New Year's Honours
We would like to congratulate Professor Sally Casswell, a current member of the Marsden Fund Council, who was appointed an Officer of the New Zealand Order of Merit in the New Year's Honours list. Congratulations, too, to former Marsden researcher, Emeritus Professor Wes Sandle (University of Otago) who was also appointed an Officer of the New Zealand Order of Merit and current researcher Professor Margaret Brimble (The University of Auckland) who was appointed a Member of the New Zealand Order of Merit.
Visit to HRC
In January, Peter Gilberd and I visited the Health Research Council in Auckland.
Along with the Foundation for Research,
Science and Technology, the Health Research Council and the Royal Society are
the main funding agencies in R,S&T. It is important that all three funding
agencies are aware of each other's programmes, not least because of the impact
that they have on researchers. We appreciated the hospitality of the CEO, Dr
Bruce Scoggins, and his members of staff, and swapped several ideas. The HRC
outlined its web-based electronic reporting, and other electronic systems. The
Marsden Fund will be trialling a web based reporting system shortly.
Research stories
The Marsden Fund supports several projects associated with Antarctica; in this issue stories on three of those projects are featured, in physics, biology and evolution. However, a feature of Marsden is its diversity, and there are also stories on education, economics, mathematics, ecology and literature. Please keep the stories coming!
| Numbers of preliminary proposals, by panel. The numbers include proposals sent to more than one panel, so adding up the number of proposals in each panel gives a total greater than the number of separate proposals given above. Last year's figures are given in brackets. | ||||
| No. of Fast-Start Proposals |
No. of
Standard Proposals |
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| Panel |
Preliminary
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Full
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Preliminary
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Full
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||||
| Biomedical Sciences |
15 (14)
|
4 (5)
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101 (87)
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18 (18)
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| Cellular, Molecular & Physiological Biology |
20 (14)
|
4 (5)
|
120 (103)
|
22 (22)
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|
Ecology, Evolution and Behaviour |
32 (18)
|
6 (4)
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131 (99)
|
22 (20)
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Earth Sciences and Astronomy |
15 (12)
|
4 (3)
|
97 (61)
|
17 (12)
|
| Humanities |
22 (7)
|
4 (3)
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46 (43)
|
8 (9)
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Mathematical and Information Sciences |
36 (12)
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6 (3)
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70 (53)
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13 (12)
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Physical Sciences and Engineering |
35 (15)
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6 (4)
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106 (111)
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22 (23)
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| Social Sciences |
65 (41)
|
15 (10)
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118 (89)
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26 (19)
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Total |
240 (133)
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49 (37)
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789 (646)
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148 (135)
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Dr Margaret Walshaw
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It is generally agreed that being good at maths is a real plus in society, but traditionally, girls have had more trouble achieving in mathematics education than boys. These days, however, things have changed, and girls are doing as well as, if not better than, boys in maths. These figures would seem to indicate that girl-power has made its debut, and that New Age women have what it takes for success as responsible numerate citizens. But does this new success in mathematics actually represent what is happening when it comes to the success of women in the real world?
Dr Margaret Walshaw of the Department of Technology, Science and Mathematics Education, at Massey University, is trying to find the answer to this question. Funded by a Fast-Start Marsden grant, Dr Walshaw's national study, "Girl Power: Explorations into the making of our future numerate citizens", is aimed at gaining a better understanding of the connections between girls, mathematics and social practices.
"There have been many heated discussions about girls and mathematics", says Dr Walshaw, "and it has taken researchers decades to understand why girls in the past have not performed as well as boys, and why they have tended to opt out of senior maths courses". A number of experts, she says, were sure that girls did not have the right sort of biological make-up that equipped them for maths achievement.
In more recent times, explanations have focused around evidence from classroom research that indicates that girls like to work in groups, and help each other. Research also indicates that girls ask fewer questions in class than boys, and attribute good results to hard work and effort. Dr Walshaw notes that some academic scholars have also supported claims that girls tend to see the world differently from men, in that they look at the world in terms of connectedness. This research has resulted in a more girl-friendly mathematics school curriculum, with more relevance to the lives of girls.
As a result, girls are now achieving as well as, or even better than, boys in maths.
Such a result should theoretically mean that women now have the same access as men and boys to the reason and logic which is crucial for mathematical literacy, and hence ultimately the same access to economic and political power. But is this new female know-how truly representative of what is actually happening for girls once they leave the school environment? Unfortunately, research shows that this is not necessarily the case. "Despite the advances made by girls in maths", says Dr Walshaw, "the fact is, that post-school options for girls are far from optimistic". Job opportunities for women are worse than for men with similar education and experience, Dr Walshaw points out. Women are concentrated in fewer jobs than men, and generally the higher proportion of women in an occupation, the lower the average pay. Girls' progress, relative to boys' progress in mathematics, has not been reflected in the workplace.
Dr Walshaw's study aims to investigate this phenomenon in more detail, by studying primary school age girls in their efforts to learn maths. The aim is to untangle the complex ways in which classroom conditions, social determinations and circumstances are tied to the mathematical minds of girls. The research on the one hand is a study of girls and their mathematics education, and on the other hand looks at wider issues, in particular, the role of girls in today's society.
The research involves working with three groups of six year old girls, from three different schools, which differ in areas such as culture, geography, ethnicity and religion, as well as parental education and employment. Thirty-three girls and their families are involved in the research. The study involves the use of audio diaries, in-depth interviews of the girls and their parents, field notes and examination of examples of the students' work. The project involves school visits, as well as home-based visits to learn more about the girls' families perceptions of maths, their views of their daughter's achievements, and their hopes for their futures. Overall, Dr Walshaw aims to uncover just what it means to be a future female numerate citizen in New Zealand.
The study is now into its second and final year. "One thing is clear", says Dr Walshaw, "the issue about girls, maths and society is much more complex than originally imagined".
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For more information, contact
Dr Margaret Walshaw Department of Technology, Science and Mathematics Education Massey University Private Bag 11-222, Palmerston North Tel: (06) 356 9099 ext. 8782 Email: m.a.walshaw@massey.ac.nz |
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Dr Kenneth Carlaw
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In the world we live in today, rapid advances in technology are a common-place occurrence, both in our everyday lives, and in industry. Research has shown that growth in technology has been one of the major contributing factors to the rise of living standards in the Western world. One of the major benefits of technology is that it allows us to be more productive - for example, rapidly advancing computer technologies mean that we can be more efficient in our day to day working lives.
It is often assumed that the increased productivity that accompanies advances in technology happens immediately. However, research over the last two decades has shown that this is not always the case. Paradoxically, many countries have found that after the arrival of new technologies, measured productivity can actually slow for some time, while the new technology is being established. This phenomenon is known as the 'productivity slowdown', or 'productivity paradox'. Now, Dr Kenneth Carlaw from the Department of Economics at the University of Canterbury is conducting research, funded by a Fast-Start Marsden grant, to study this phenomenon in more detail.
Productivity slowdowns have been associated with many major technological advances in recent times. Examples include the first industrial revolution, which began in the late 18th century following the invention of the steam engine, the second industrial revolution, which occurred in the late 19th century following the development of the steel industry and giant corporations, the electrification of US manufacturing, and the introduction of information and communication technologies.
The reason for this phenomenon, Dr Carlaw explained, is that new technologies emerge in crude, underdeveloped form, almost always requiring the invention and development of complementary technologies. It is only once these technologies become established, that large-scale productivity gains can be made. "A great deal of upfront investment and further innovation must take place before the productivity gains associated with a new technology can be realised", Dr Carlaw said. "This investment and subsequent innovation takes time".
Dr Carlaw's research has involved measuring productivity and technological change in a collection of 14 OECD economies (including New Zealand) and within the industries of New Zealand. As Dr Carlaw anticipated, results have revealed the general trend that when investment quality change (a measure of technological change) goes up, productivity decreases. This result lends support to the theoretical predictions of productivity slowdowns when major new technologies emerge. Dr Carlaw's research has resulted in the development of a new theoretical model of general purpose technology driven growth.
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| The New Zealand data, showing that the measure of technological change, "investment quality change", moves in the opposite direction to the growth rate of productivity. This is a general result across almost every country in the comparison. |
The results of the research make it clear that when predicting future economic performance, productivity statistics must be considered, as well as other, more traditional measures of the economy. The research has drawn interest from researchers in the Ministry of Economic Development, the Reserve Bank, and Treasury, and recently, the Australian National Office for the Information Economy, all of whom are trying to understand how technological change drives economic growth.
More research in this area is planned for the future. "One major future goal", says Dr Carlaw, "is to use the model of general purpose technology driven growth to develop a theory of productivity which will allow economists to understand how technology actually manifests as economic growth".
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For more information, contact
Dr Kenneth Carlaw Department of Economics University of Canterbury Private Bag 4800, Christchurch Tel: (03) 364 2846 Email: kenneth.carlaw@canterbury.ac.nz |
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Robin Hyde (1906-39) was a highly regarded New Zealand journalist, novelist, and poet. During her short but productive life she wrote numerous newspaper articles, five novels, as well as more than 500 poems. Now, a major collection of her poetry, nearly 350 poems in all, has been assembled chronologically, and illustrated with a series of stunning, previously undiscovered photographs.
Young Knowledge: The Poems of Robin Hyde is edited and introduced by Associate Professor Michele Leggott, from the Department of English at The University of Auckland, and published by Auckland University Press. It is part of a comprehensive study of Hyde, funded by a Marsden grant, which has also involved Drs Mary Paul and Patrick Sandbrook from Massey University, Hyde's son Derek Challis, and Dr Lisa Docherty, who completed her PhD with the support of the project.
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Te Papa Tongarewa / Spencer Digby collection
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Robin Hyde was born in South Africa, and became well known in New Zealand in the 1920s and 1930s as a journalist. During this time, she also published her five novels, a book of her experiences as a journalist, as well as three volumes of poetry. In 1938 Hyde began a trans-Siberian railway journey to London. However, before she could reach her destination, she was diverted to mainland China, which had been invaded by the Japanese. After spending some time travelling in China, she was detained by Japanese troops. Hyde finally arrived in London in September 1938. Tragically, she committed suicide in 1939, just before the outbreak of war in Europe.
Michele Leggott first became interested in Robin Hyde after reading her autobiographical fragment A Home in This World. "The writing is fabulous, the narrative heart-breaking, and the sense of purpose overwhelming", Leggott said. "I hadn't known there was this strong, funny, rebellious female voice to be found in New Zealand's literary history. That she was also a poet, and the poetry might carry those same qualities, was an irresistible thought."
The project to compile a book of Hyde's poetry began in 1993 when Leggott discovered that The University of Auckland library holds most of Robin Hyde's poetry manuscripts, with the balance held by Hyde's son and biographer, Derek Challis. The project was completed last year with the publication of the book.
Together with the collection of Hyde's poetry, the book features a number of striking photographs of Hyde. They were taken in 1936 by Wellington photographer Spencer Digby, when Hyde was visiting her family in Wellington. The photographs are haunting, with lighting effects used to highlight Hyde's features to stunning effect.
The photographs of Hyde had been hidden from public view for quite some time before they were included in the book. Michele Leggott's first clue to their existence was a reproduction of one of the images in a 1938 magazine. Intrigued by Hyde's haunting expression, Leggott decided to try and obtain a copy for the front cover of the book. This initially proved difficult, but a visit to Lucy Alcock's Persephone in Winter exhibition revealed the same print, uncropped and positioned above a case containing Hyde's moonstone ring, the light from which features in the photo. "It was amazing to see the photo like that", Leggott said.
Collaborative efforts revealed the existence of several more portraits. The print in the exhibition turned out to be part of the Turnbull Library's photographic collection. The date on it then led to searches of the Te Papa archives, which subsequently revealed the portrait negatives, which had lain in Digby's archive, mislabelled and uncatalogued. "There were five of them", Leggott explained, "and there were five sections in Young Knowledge". "It didn't take long to decide that each section should lead off with a portrait".
As well as being striking to look at, the photographs were also taken at an interesting time in Hyde's life. She had just spent three years at The Lodge, which was part of the Auckland Mental Hospital. "They are taken at the exact moment of her first step away from the security of The Lodge", said Leggott. "It was her first long parole from the hospital, where she had been a voluntary boarder since her breakdown of mid 1933". Hyde's stay at The Lodge is regarded as an important stage of her career, as part of her therapy was to express herself by writing, something she did with great success.
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Final section of 'Fragments from Two Countries' by Robin
Hyde.
In the days before tempest, (my head will be good as the next!) I dream so much of the poems made in my youth. Small idle ghosts I had written, forgotten, never since seen, Slip into my brain; say, 'We were a part of you,' As swiftly are gone again. A soft might carries us on. It is like the wind, streaming over Wellington hills, Which, bearing all sunset's flame, scorns not the kites: It is like the tide, flowing out from Island Bay, Bubbling round dinghies, it lifts the children's boats. This poem was written in April 1938 when Hyde had reached Hankow, the war-time capital of China, after a hazardous railway journey from Canton in the south. She was in Hankow for three weeks, waiting for a pass to the northern battlefront. During that time she began assembling as verbal snapshots some of the material she had noted in Hong Kong, Shanghai and Canton, juxtaposing the impact of the Asian present with vivid memories of her Wellington girlhood that recurred as dreaming and waking vision. This fragment captures the overlay perfectly. |
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The New Zealand Electronic Poetry Centre website: www.nzepc.auckland.ac.nz is a project to set up an electronic gateway to poetry resources in New Zealand and the Pacific region. The website presents electronic publications of poetry, including full-text poems, and audio and video files, together with commentary, and information about individual poets, including photos, bibliography and biographical information. There are also links to other poetry-related websites. The project is based at The University of Auckland, and is being developed by Michele Leggott of the English Department and Brian Flaherty of the University Library, supported by Auckland University Press and the Faculty of Arts. The website features an author page on Robin Hyde and her poetry: http://www.nzepc.auckland.ac.nz/authors/hyde/. Also associated with the website are 97 pages of notes that accompany the text of Young Knowledge: The Poems of Robin Hyde. This innovative move means that the book itself does not contain any scholarly notes, keeping its length to a manageable level. Instead, interested readers are directed to the readily accessible location of the notes on the NZEPC website. For more information, contact
Associate Professor Michele Leggott Department of English The University of Auckland Private Bag 92-019, Auckland Tel: (09) 373 7599 ext. 87342 Email: m.leggott@auckland.ac.nz |
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| An example of a coastal ice-free area of Antarctica (in this case Cape Hallett), habitat of the Antarctic nematode. (Photo Craig Marshall) |
More than 99% percent of Antarctica is permanently bound by snow and ice, and the small areas that are ice-free can give the initial impression that they are nothing more than a barren wasteland. However, look closely and it becomes clear that they are actually teeming with life. The phrase 'Antarctic animals' usually leads to images of penguins and seals. These, however, are actually part of the marine ecosystem. The true Antarctic animals, ones that live on the continent all year round, are in fact microscopic, and include several species of nematode worms.
Like other Antarctic animals, these nematodes need to be extremely tolerant of low temperatures. As well as the intense cold during the winter, in the spring their habitat is often saturated with water and the nematode experiences regular potentially lethal cycles of freezing and thawing. Only during the summer do the areas that they live in receive sufficient meltwater to support their growth. These animals are living at the limits of life on Earth, surviving extreme cold and desiccation, and are constantly exposed to the risk of freezing. Just how do they manage to survive in such a difficult environment?
On his first visit to the Antarctic in 1989, Associate Professor David
Wharton of the Department of Zoology at Otago
University isolated one of these nematodes, Panagrolaimus davidi,
from the McMurdo Sound area. A tiny one millimetre in length, this nematode
proved remarkably tolerant of both freezing and desiccation, enduring freezing
for at least nine months. Now, Professor Wharton, together with Dr Craig Marshall
of the Biochemistry Department, and postdoctoral researcher Dr Gordon Goodall
have been conducting research, funded by a Marsden grant, to examine just how
this remarkable animal manages to survive such extreme conditions.
There are a variety of mechanisms used for survival by animals that live in cold conditions. Antarctic birds and mammals, for example, can generate their own heat. Animals such as nematodes cannot do this, and risk freezing when temperatures fall much below zero degrees. As a result, they have evolved their own techniques to prevent this problem. These fall into two broad categories. Freeze-avoiding animals can prevent themselves freezing altogether, maintaining their body fluids in a liquid, supercooled state. Freezing-tolerant animals, on the other hand, can survive ice forming within their bodies. However, it is usually thought that these animals can only survive ice formation outside their cells, and that freezing within cells is fatal. This idea though, has rarely been tested.
Professor Wharton's research into the cold-tolerance mechanisms of P. davidi has revealed that the nematode can actually survive freezing within its cells, making it the only animal known to do so. The research has shown also that the nematode has other responses to freezing, depending on the conditions. If frozen very slowly, for example, at a temperature just below zero, the nematode will dehydrate rather than freeze. The nematode can also survive the formation of ice outside its cells, a fact that was discovered using techniques that allow the visualisation of ice in the animal under an electron microscope. P. davidi thus has a variety of mechanisms that ensure its survival in its harsh Antarctic habitat.
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| Scanning electron micrograph of the Antarctic nematode Panagrolaimus davidi. Actual size is approximately one millimetre long. Nematodes are a phylum of worms that are extremely abundant. About half the described species of nematodes are parasites of animals and plants, the remainder are free-living in soil, freshwater and marine habitats. |
The research team has also investigated the finer details of the mechanism the nematode uses to survive freezing conditions. It is known that other cold tolerant organisms produce a diversity of 'ice-active' proteins, which affect the formation and stability of ice. Professor Wharton and his colleagues have now shown that P. davidi produces a previously unknown type of ice-active protein that has the properties of inhibiting the growth of ice crystals after their formation, a phenomenon which could be damaging if it occurred within a living animal. The protein may also inhibit the initiation of freezing.
The nematode ice-active protein belongs to a large family of nematode-specific proteins. These show a weak similarity to a family of vertebrate proteins that are used in hormone transport in the blood, but have never before been seen to function as ice-active proteins. Surprisingly, there is no similarity between the nematode proteins and other ice-active proteins such as the antifreeze proteins of polar fishes or the ice-inhibiting proteins of insects.
On a wider scale, determining how these nematodes are able to survive the stresses of freezing and desiccation will assist in our understanding of how life can exist in extreme environments, and may also help in the development of new technologies for the preservation of biological materials.
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For more information, contact
Associate Professor David Wharton Department of Zoology University of Otago PO Box 56, Dunedin Tel: (03) 479 7963 Email: david.wharton@stonebow.otago.ac.nz |
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A man walks 30 m towards the East and then 50 m towards the North. How far is he from his starting point? Many of us will recall tackling such contrived geometric problems at school, using vectors. Vectors themselves are specified in terms of numbers; in this question, for example, the man's displacement is specified by the vector (30, 50). The beauty of such an approach is that a geometric problem is reduced to simple algebra.
From a mathematical viewpoint, the problem is represented by a collection of points in a plane (the starting point, the finishing point, and the point at which he changes direction), which are described geometrically by the 3 vectors which join the points. The algebraic description of the vectors is provided by numbers; these numbers are known as the field.
The problem can be extended to 3 dimensions by introducing hills, and is still relatively straightforward, but what happens if 4 or more dimensions are considered? To understand such geometric problems in higher dimensions, mathematicians have introduced the concept of a matroid (a finite collection of points in multi-dimensional space).
Matroids arise in many situations. In binary mathematics, for example, a matroid is given by a collection of binary strings (such as 1001101), and the strings are specified in terms of a field composed of just 2 elements (0 and 1). These matroids find application in computer science and information theory. Matroids based on finite fields may appear strange but are nonetheless perfectly valid geometrical objects. The diagram (p.9) shows a matroid based on a field of 3 elements.
However, going beyond fields of 4 or 5 elements, the level of difficulty escalates and a central question becomes which matroids can be represented by which fields. There are two famous conjectures in matroid theory, as yet unproven, by Rota and Wagner, that help answer this question. At the outset of his last Marsden grant, Professor Geoff Whittle, from Victoria University of Wellington, predicted that the proof of these conjectures was tens of years away. Professor Whittle likens the proof to scaling an alpine peak. To make it possible, "we have to find a way to the peak; this involves bridging chasms, finding routes through jungles, fording rivers". Now, as a result of the Marsden grant, he predicts that the conjectures will be proved in just a few years. "Of course, it is always possible that the conjectures may be false. But we believe that they are true. Sadly, in mathematics, intensity of belief is no substitute for proof."
As well as making remarkable progress on the maths, the research team has enjoyed considerable personal success. Geoff Whittle was promoted to professor and elected as a Fellow of the Royal Society of New Zealand. One of the overseas collaborators and an associate investigator on the grant, Professor Jim Geelen from the University of Waterloo in Canada, received the prestigious Fulkerson Prize for an outstanding paper in the area of discrete mathematics. The postdoctoral fellow, Dr Petr Hlineny, wrote a public domain program which is becoming the standard computational tool for matroid researchers worldwide. The two Masters students, Rhiannon Hall and Dillon Mayhew, both received Commonwealth Scholarships to undertake doctoral studies at Oxford. Another collaborator, Dr Charles Semple, who had been a student on the preceding Marsden grant and won the Hatherton award, took up an appointment at Canterbury University, has received Marsden funding in his own right, and last year received the Hamilton Memorial Prize.
Matroid theory has deep connections with graph theory, not the familiar graphs from school, but mathematical models for such things as road networks and wiring diagrams. Graph theory has been one of the most rapidly developing branches of mathematics over the last 30 years because of its connections with computer science. Some of the deepest results in the theory have been obtained in a famous series of papers by mathematicians, Neil Robertson and Paul Seymour. The challenge for Professor Whittle and other leading mathematicians in the field is to achieve analogous results for matroids.
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For more information, contact
Professor Geoff Whittle School of Mathematical and Computing Sciences Victoria University of Wellington PO Box 600, Wellington Tel: (04) 463 5650 Email: geoff.whittle@vuw.ac.nz |
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Parasitised cockles lying at the surface of a mudflat
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Parasitic organisms living inside an animal can have a major effect on how the animal goes about its daily life, influencing how it behaves, how fertile it is, and even where it chooses to live. Now, research being carried out by a team from the University of Otago is suggesting that parasites infecting individual animals may have dramatic effects not only on the animal itself, but on the entirety of the surrounding ecosystem. The good news is, the effect is not always a negative one.
A common measure that ecologists use when studying an animal community is biodiversity, or the number and variety of species that exist in a particular environment. Biodiversity can vary a great deal, even among habitats that otherwise appear to be quite similar. A major goal of ecologists is to understand just how biodiversity is maintained in natural systems. The forces controlling biodiversity in any given locality are complex, but research has suggested that parasitic diseases may have a significant influence on biodiversity in different habitats.
Until recently, there has been no comprehensive study of the impact of parasites on an entire animal community, and many questions about the effects of parasites on biodiversity have long remained unanswered. For example, if a parasite affects a 'keystone' member of the community, could this have an indirect impact on the diversity of the entire community? And what is the overall influence of all parasite species on local biodiversity?
Funded by a Marsden grant, a research team led by Professor Robert Poulin and Dr Kim Mouritsen has been studying these and other related questions, in order to determine just what impact parasites can have on entire animal communities. Specifically, the team are using the New Zealand intertidal mudflat ecosystem as a model system. Intertidal mudflats provide an excellent opportunity to answer questions regarding the impact of parasitism on biodiversity, as they are readily accessible, and are amenable to a range of field experiments. So far, the team has conducted field experiments which involved manipulating the abundance of parasitised hosts, in order to demonstrate that one particular parasite species can have an effect on the overall animal biodiversity of mudflats.
For their research, Professor Poulin and Dr Mouritsen focused on a parasitic flatworm, Curtuteria australis, which forms cysts in the foot of cockles. Cockles are the dominant bivalves in New Zealand's intertidal mudflats. Normally, they bury themselves a few centimetres under the sediment surface. However, infection with Curtuteria australis impairs the ability of the cockles to burrow. Heavily infected cockles must therefore remain stranded at the surface of the mudflats, and so, in areas of intense parasitism, many cockles are either protruding from the sediments, or merely lying at the surface. Parasitism therefore results in a change in the structure of the surface of the sediment, making it more complex and uneven, which in turn has effects on water flow and the sedimentation process. In this way, the parasite indirectly causes microhabitat changes that may affect the settlement and survival of all other species in the region.
Surprisingly, the researchers have found that the presence of this particular parasite on a mudflat actually leads to greater biodiversity, having found that 15-20% more invertebrate species settled in experimental plots seeded with heavily parasitised cockles than in control plots. Parasites, it seems, may be making a positive contribution to biodiversity in certain situations.
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Professor Robert Poulin
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As well as their research on cockle parasites, the team is also examining the impact of other parasite species on the population dynamics of their hosts. For example, they have discovered that on mudflats in the Otago Harbour and adjacent areas, the local density of many important species of molluscs and crustaceans is actually depressed by the presence of their specific parasites, a contrast to the situation with the cockle flatworm.
Professor Poulin, Dr Mouritsen and their colleagues are gradually putting together a complete picture of the intertidal community that includes all major parasite species. Overall, the research has two immediate goals. First, the researchers plan to generate models of the intertidal food web, and assess the contribution of parasites to its stability and resilience to changes. Second, they will construct different models to predict how climate changes, such as slight increases in temperature, might influence the abundance of parasites and their impact on community structure and biodiversity.
During the course of the study, the researchers have discovered several interesting new species of parasites, most of which are not yet formally named and described. While parasitism modulates the abundance and diversity of the animals that the human eye can see, we are only just beginning to appreciate the diversity of the invisible fauna of parasites living within them.
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For further information, contact
Professor Robert Poulin Department of Zoology University of Otago PO Box 56, Dunedin Tel: (03) 479 7983 Email: robert.poulin@stonebow.otago.ac.nz |
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Professor Diana Hill |
Global Technologies (NZ) Ltd
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Dr Garth Carnaby
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Canesis Network Ltd
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Professor Rob Ballagh
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University of Otago
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Professor Pat Bergquist
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The University of Auckland and Macquarie University
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Professor Sally Casswell
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Massey University
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Professor Marston Conder
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The University of Auckland
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Professor Charles Daugherty
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Victoria University of Wellington
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Mr Jonathan Mane-Wheoki
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Te Papa Tongarewa
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Professor Pat Sullivan
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Massey University
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Dr David Wratt
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National Institute of Water and Atmospheric Research Ltd
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Dr Don Smith, Manager. Tel: 04-470 5776; Email: don.smith@rsnz.org
Dr Peter Gilberd, Deputy Manager. Tel: 04-470 5778; Email: peter.gilberd@rsnz.org
Dr Rachel Averill, Research Assessor. Tel:04-470 5774: Email: rachel.averill@rsnz.org
Dr Tasha Black, Research Assessor. Tel: 04-470 5774; Email: tasha.black@rsnz.org
Rochelle Barton, Administration Officer. Tel: 04-470 5799; Email: rochelle.barton@rsnz.org
Janet Sorensen, Administration Officer. Tel: 04-470 5788; Email: janet.sorensen@rsnz.org
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Marsden Update is published quarterly by the Marsden Fund and is available free on request. Editor: Anna Meyer. Email: ameyer@paradise.net.nz